In the prior art, a gasoline engine may include a port type fuel injection valve that injects fuel into an intake port, a direct injection type fuel injection valve that directly injects fuel into a cylinder, or both of these fuel injection valves. Further, patent document 1 describes a gasoline engine that includes both of the port type fuel injection valve and the direct injection type fuel injection valve and a controller that controls the gasoline engine.
The exhaust from a gasoline engine includes particulate matter (PM) and atmosphere pollutants such as carbon monoxide and hydrocarbons. The emission of such pollutants has been regulated in the past and is now being further strictly regulated. More specifically, tests are conducted on gasoline engines to capture the PM suspended in the exhaust and measure the mass of the captured PM. The mass of the captured PM needs to be less than or equal to a reference value.